AN ISOPLANAR ISOLATION TECHNOLOGY FOR SIC DEVICES USING LOCAL OXIDATION

This article presents the feasibility of extending the well-known Si L OCOS (localized oxidation of Si) technology to SiC. Two isolation proc esses have been structurally evaluated to find an optimal, isoplanar i solation technology for SiC device integration. The first is an extens ion of the conventional LOCOS process which exploits the differential oxidation ratio between SiC and Si3N4. The second technique, called th e '' field-poly'' process, uses a selective oxidation of polysilicon o ver SiC to form the isolating field region. Scanning electron microgra phs show the typical bird's beak around the active area border with a width of 0.92 mum per side for the LOCOS process (field oxide = 3000 a ngstrom) and 0.55 mum per side for the field-poly process (field oxide = 8000 angstrom). Compared to the mesa isolation currently used for S iC, the new technologies improve structural planarity while allowing s elf-aligned field threshold implants for isolation between adjacent de vices.